Machines that munch through trees in seconds are being used to speed up the restoration process in one of the UK’s most important peat habitats.

Demand for timber in the post-war era saw spruce planted in the unique Border Mires network near Kielder Water in Northumberland, with drainage put in to help them grow.

That dried out the nationally important sphagnum bog and the tree cover blocked out light in an environment where rare plant species should thrive.

The mires, formed 12,000 years ago as the Ice Age ended, were also a useful hideout in the 17th century for Scottish cattle rustlers who used their knowledge of its paths to escape the English authorities.

Now Forestry England is restoring the bogs using specially designed tree mulchers to rip down the spruce in seconds.

The machines’ wide tracks stop them sinking in the bog and their powerful cutting discs can turn trunks into chips, which are left in place to degrade.

Once an area is cleared, the drains will be blocked and the mire will be allowed to fill with water again.

While cutting down trees might seem to go against green thinking, bogs are great carbon stores.

Forestry England ecologist Wayne Penrose, who is overseeing the work on the ground, said: “These mires are incredibly important.

“They date back to the end of the last Ice Age, 12,000 years ago, and so represent one of the most natural of all UK habitats.

“Not only do they support a fantastic array of plants and animals, including sphagnum moss, bog asphodel, sundews, dragonflies and wading birds, but they also lock away carbon in the peat.

“Because of this they play a crucial role in mitigating the effects of climate change.

“We will also remove smaller spruce with chainsaws at three other locations, covering 161 hectares (398 acres), and blocking 3.5 kilometres (2.2 miles) of drainage channels so the land retains water, the lifeblood of a bog.”

Angus Lunn, vice-president of the Northumberland Wildlife Trust, said: “It is exactly 50 years since a group of Northumberland Wildlife Trust volunteers, armed with spades, installed the first peat dams in drains in the Border Mires.

“It is a great satisfaction that collectively we have accomplished so much over the years in what was the first major peatland restoration project in Britain.

“Some people may think bogs are not as beautiful as ancient woods or rainforests, but they are an incredibly valuable habitat and part of a rich mosaic of landscapes in Kielder Forest.”

The mires, 15m (49ft) deep in places, hold more liquid than Kielder Water, which is Europe’s largest man-made lake.

The Scottish cattle rustlers, often ex-soldiers disbanded following the Civil War, became known as “Moss Troopers”.

Such was their notoriety that legislation was introduced to curb their activities and they were also effectively excommunicated by the church.